1. Field of the Invention
The present invention is directed in general to the dispensing of viscous liquids and in particular to the ability of particular plastics to shrink thereby creating a volumetric reduction in a container made of said plastic which induces a flow of the charge.
This invention also relates to delayed dispensing. Non-immediate dispensing is often required for lubricants for lubrication of fixed and mobile equipment, inks for re-inking of printer ribbons, additives for replenishment of lubricant additives, or medications for ambulatory drug maintenance. Lubricant dispensing units may be independent or tied to a central control system.
2. Description of the Prior Art
This invention employs the ability of various plastics which shrink either due to form memory, polymerization, or chemical action. Heat activated, form memory plastics which have been fabricated into film, sheets, or tubing are widely used in packaging, assembly, and electrical connections. Other uses include encapsulation disclosed in U.S. Pat. No. 4,915,139, and a Self-Extinguishing Cigarette disclosed in U.S. Pat. No. 3,091,243.
It is the general object of this invention to provide a simple, reliable, inexpensive shrink induced dispenser where immediate application of the charge to be dispensed is either untimely, inconvenient, hazardous, or inaccessible.
This invention teaches that shrink induced dispensing can be utilized for a variety of charge viscosities by varying the dimensions of the container. For example viscous liquids can be displaced by the shrinkage of thick walled, small diameter tubes. Low viscosity liquids can be displaced by thin walled containers.
This invention teaches that shrink induced dispensing can be activated by a variety of means by varying the container's plastic material. The Modern Plastics Encyclopedia, Volume 63, Number 10A, page 792 lists ten plastics used in shrink tubing supplied by twenty-nine companies. The predominate shrink plastics in current use are heat activated, form memory polymers. Plastic materials exist which shrink under conditions of aging, polymerization, light, exposure to air, or chemical action. Thereby, a variety of applications can be served by a plastic selection which corresponds to the desired mode of dispensing in terms of activation method, time interval of delay, and duration period of dispensing.
Automotive centralized lubrication in the prior art is a complex method of lengthening maintenance intervals. All the systems shown in The Application of Centralized Lubrication Systems to Mobile Equipment, SAE #750585, require a pump. The use of electrical resistance heating to activate heat shrink induced lubricant dispensing eliminates the pump. Dispensing is aided by the heat being applied to the charge, thereby improving the flow of a viscous charge. A heat activated grease dispenser when insulated can function at lower ambient temperatures than the prior art. Thus, it is a more particular object of this invention to provide an inexpensive dispensing element for multi-outlet dispensing systems.
Further, this invention teaches that shrink induced dispensers can eliminate a dispensing controller by making the controller integral with the flow inducing member. U.S. Pat. No. 4,886,144 discloses a Lubricating Apparatus for Bearings. This is an example of the prior art wherein a spring induced dispenser is a separate member from it's temperature control. During operation a machinery bearing may heat in the absence of lubrication. Such heat when transmitted to a lubricant charged, heat activated, shrink induced dispenser can automatically dispense on a demand basis. Lubricant use can be optimized in the absence of a unified system or external control by the invention's temperature responsive automatic flow control. Thereby, this invention can also supply fall-back lubrication which is heat activated if routine lubrication is omitted.
After use, printer ribbon within a cartridge may require re-inking. U.S. Pat. No. 4,747,711, Cartridge for an Inked Ribbon with a Re-inking Device, discloses an ink charged reservoir discharge by wick action. A shrink induced dispenser which has a container that is activated by exposure to air can provide delayed reinking in parallel with ink usage as the recycled ribbon carries ambient air into the cartridge.
Automotive engine crankcase lubricants often require replenishment of their additives after a defined period in operation. U.S. Pat. No. 4,075,098, Masking Elements for Dissolving Oil Improving Body in an Oil Filter, discloses a way of delaying the dispersal of these additives from a source body within an oil filter canister. This delayed dispensing of chemical additives can be more easily accomplished by a shrink induced dispenser selected to age shrink within the ambient conditions of engine oil. The inexpensive nature of shrink tubes allows for the segregation of incompatible additives within separate dispensers. Thus, another object of this invention is independent, integral, automatic delayed dispensing over a period of months to extend the useful life of disposable or recyclable components.
Medical prior art includes a number of devices for infusing a drug to an ambulatory patient. U.S. Pat. No. 4,692,151, Parenteral Fluid Medication Reservoir Pump, discloses two pumpless methods for induced flow, either by balloon depletion or by expansion of a compressed gas. Such pressurized systems tend to dissipate during storage and have no delayed discharge ability. An infuser for an ambulatory patient using the pumpless dispensing ability of a shrink induced dispenser has storage integrity and an activation delay period selected to conform to the medication charge. Thus, another object of this invention is delayed automatic ambulatory medication.